Turbo Machine

ABSTRACT

A turbo machine ( 1, 101 ), in particular turbine or compressor, includes a rotor ( 2, 102 ) which has at least one moving blade row ( 4, 104 ) with a plurality of moving blades ( 5, 105 ), and a stator ( 3 ) which has at least one guide vane row ( 6, 106 ) with a plurality of guide vanes ( 7, 107 ), at least one moving blade row ( 4, 104 ) having a shroud ( 8, 108 ). The shroud ( 8, 108 ) is designed to be self-supporting in such a way that it can at least partially absorb the centrifugal forces arising during operation and discharge them in the circumferential direction.

This application is a Continuation of, and claims priority under 35 U.S.C. § 120 to, International application no. PCT/EP2006/065879, filed 31 Aug. 2006, and claims priority therethrough under 35 U.S.C. §§ 119, 365 to Swiss application nos. 01508/05, 01509/05, both filed 15 Sep. 2005, the entireties of which are incorporated by reference herein.

BACKGROUND

1. Field of Endeavor

The present invention relates to a turbo machine, in particular a turbine or a compressor, and, moreover, relates to a shroud or shroud ring for a turbo machine.

2. Brief Description of the Related Art

Turbo machines, such as turbines, in particular gas turbines and steam turbines, and also compressors, include a rotor which is mounted rotatably in a fixed stator. Turbo machines of this type are also designated as rotating turbo machines. The rotor in this case regularly includes a plurality of moving blade rows which in each case include a plurality of moving blades. Correspondingly, the stator usually has a plurality of guide vane rows which include, in each case, a plurality of guide vanes.

In this context, it is basically known to provide the moving blade rows and/or the guide vane rows with a shroud which, in the mounted state, possesses an annular arrangement and connects the free blade or vane ends of adjacent blades or vanes to one another within the same blade or vane row. With the aid of shrouds of this type, the aerodynamics of the respective blade or vane row can be improved, thus increasing the efficiency of the turbo machine equipped with them. Furthermore, shrouds of this type lead to stabilization by virtue of the circumferential support of large blades or vanes which, because of their radial length, exhibit a certain tendency to oscillate when the turbo machine is in operation.

GB 1 509 185 A discloses a moving blade row, in which the individual moving blades are connected to one another in the region of their blade tips via shroud segments arranged between them.

Insofar as the shrouds are also used as axial seals for individual blade rows, they may be exposed to increased wear, as a result of which repairs are required. Insofar as the individual shroud plates or shroud portions, which, in the mounted state, in their entirety form the respective shroud, constitute an integral part of the associated blade, this usually being the case, high repair costs are incurred, since the entire blade has to be repaired and, if appropriate, exchanged.

SUMMARY

One of numerous aspects of the present invention includes providing, for at least one moving blade row, a shroud which connects all the moving blades of a moving blade row to one another at their tip in the circumferential direction and consequently, when the turbo machine is in operation, exerts no centrifugal forces on the moving blades, but, instead, deflects and absorbs the centrifugal forces in the circumferential direction. For this purpose, a shroud is provided which is formed from a plurality of separate shroud segments, which are assigned in each case to a plurality of moving blades, or from a plurality of separate shroud plates, which are assigned in each case to a moving blade, or from a single separate shroud ring which is assigned to all the moving blades of the respective moving blade row. At the same time, the shroud ring or the respective shroud segment or the respective shroud plate is fastened to one or to a plurality of moving blades in a radial direction. In this case, this fastening is implemented by non-destructively releasable anchorings. Thus, in a turbo machine according to principles of the invention, it is readily possible to remove the shroud for maintenance or repair purposes, without individual moving blades having to be demounted for this purpose. This is advantageous particularly for those turbo machines which have moving blades formed integrally on the rotor or on the stator. Furthermore, such a combination affords the possibility of retrofitting the shroud, that is to say of subsequently equipping a moving blade row of a turbo machine with the shroud. Thus, in such a turbo machine, stabilization by the circumferential coupling of long moving blades and/or improved aerodynamics can subsequently be achieved.

Furthermore, the shroud ring built onto the moving blades or the respective shroud segment or the respective shroud plate is a separately produced component, thus affording the possibility of using different materials and/or different material structures for the production of the shroud, on the one hand, and for the production of the moving blades, on the other hand. For example, moving blades in gas turbines are often produced from monocrystalline superalloys and optimized in terms of radial loads. In contrast to this, the shroud may be equipped, for example, with a different elasticity and be optimized for tangential loads. Moreover, owing to the separately produced shroud formed by the shroud ring or by the shroud segments or by the shroud plates, there is the possibility of optimizing the shroud in terms of the required strength by a suitable choice of material and in terms of aerodynamics by appropriate contouring.

According to an advantageous embodiment, the anchoring may have at least one anchor receptacle which has a reception profile which is constant in a longitudinal direction of the anchor receptacle and is open radially on one side and has at least one undercut accessible radially to engagement. Furthermore, the anchoring may have at least one anchor with an anchor profile configured complementarily to the reception profile and which can be inserted into the anchor receptacle, so that its anchor profile is in engagement with the at least one undercut of the anchor receptacle. Thus, by the anchoring, a positive and particularly load-bearing mechanical connection is made between the respective moving blade and the shroud ring or the respective shroud segment or the respective shroud plate.

In this case, it is basically possible to form the anchor receptacle in the shroud and to form the fitting anchor, preferably integrally, on the respective moving blade. It is likewise possible to form the anchor receptacle on the respective moving blade and to form the associated anchor, preferably integrally, on the shroud. In a further alternative, it is possible to design the shroud and the respective moving blade with anchor receptacles lying opposite one another, so that a separate, additional anchor body, which has two anchors, can be inserted simultaneously into both anchor receptacles. With the aid of an additional anchor body of this type, the mounting and demounting of the shroud can be simplified considerably.

The use of anchors and anchor receptacles of this type leads additionally, besides the radial securing of the shroud to the moving blades, to a fixing of the shroud transversely to the longitudinal direction of the anchor receptacles. Thus, in the case of an axially oriented anchor receptacle, fixing occurs in the circumferential direction. Insofar as the anchor receptacle is inclined with respect to the axial direction, moreover, this results in holding forces in the axial direction.

A further advantage is seen in that, in the case of a distortion of the moving blades, at least elongate anchors lead additionally to a nonpositive securing of the shroud to the moving blades. When the turbo machine is in operation, in particular, large moving blades which are comparatively long in the radial direction may be distorted due to the flow forces and centrifugal forces which arise. Since the anchor and the associated anchor receptacle necessarily have to be oriented parallel to one another for mounting, distortion leads to the tilting or jamming of the anchor in its anchor receptacle.

Another aspect of the invention includes, according to an alternative embodiment, not forming the respective shroud from a plurality of shroud plates or shroud portions assigned to individual moving blades, but, instead, forming it from a single shroud ring which is assigned to all the moving blades of the respective moving blade row and which has a self-supporting configuration and is built onto the radially outer moving blade tips of the moving blade row. The self-supporting shroud ring is configured such that, particularly when it is assigned to a moving blade row, it can absorb in itself the forces arising during operation, without at the same time subjecting the moving blades to load. In particular, the centrifugal forces arising during operation can be absorbed, without a significant additional radial tensile load on the moving blades occurring at the same time. The useful life of the moving blades is thereby increased. Likewise, the moving blades may have a weaker dimensioning, which is useful for a weight reduction which increases the efficiency of the turbo machine. This is achieved by the shroud ring body, which is closed in the circumferential direction and which converts the centrifugal forces arising into tangential tensile stresses. So that the shroud ring can be built onto the moving blade, the shroud ring must be a component produced separately with respect to the moving blades. The separate production of the shroud ring makes it possible to use a material which differs from that of the moving blades and/or a material structure which differs from that of the moving blades. For example, the shroud ring may be optimized in the direction of tensile load in the circumferential direction, whereas the moving blades are usually optimized in terms of tensile load in the radial direction.

Furthermore, the shroud ring, configured as a separate component, can readily be designed such that it can be removed again comparatively simply. The repair or replacement of the shroud ring in the event of wear phenomena is thereby simplified. This is advantageous particularly in the case of rotor portions with integrated moving blades.

A further advantage is seen in that the shroud ring is basically retrofittable. Thus, moving blade rows of a turbo machine can subsequently be provided with a shroud in a comparatively cost-effective way, so that the advantages of a shroud, to be precise the stabilization of long moving blades and an increase in efficiency due to reduced leakages and aerodynamic optimization, can thereby be utilized.

In a preferred embodiment, the shroud ring may be built onto the moving blades such that it is radially free with respect to the moving blades. That is to say, the shroud ring is not fixed to the moving blades in the radial direction, but, instead, is arranged freely movable, or loosely in relation to the moving blades. Thus, for example, thermally induced stresses can be reduced. This type of construction is particularly advantageous when the shroud ring is used in a moving blade row. The centrifugal forces arising during operation force the shroud ring radially outward. Owing to the degree of freedom provided in the radial direction, the shroud ring can basically lift off from the associated moving blades in the radial direction, without tensile forces in this case being transmitted between the shroud ring and the moving blades. In terms of the centrifugal forces, therefore, the moving blades are decoupled from the shroud ring.

In this case, depending on the configuration of the coupling between the shroud ring and the moving blades, even a coupling of the moving blades in a circumferential direction to avoid the excitation of oscillations can nevertheless be ensured.

Further important features and advantages of the turbo machine according to the invention may be gathered from the drawings and from the accompanying figure description with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred exemplary embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description, the same reference symbols referring to identical or similar or functionally identical components. In the drawings, in each case diagrammatically,

FIG. 1 shows a greatly simplified basic cross section through a turbo machine in the region of a moving blade row,

FIG. 2 shows a view in the radial direction in the region of a blade according to an arrow III in FIG. 1,

FIG. 3 shows a sectional view of the blade in the region of a shroud according to the sectional lines IV in FIG. 2,

FIG. 4 shows a view in the axial direction of the blade in the region of the shroud according to an arrow V in FIG. 2,

FIG. 5 shows a view, as in FIG. 4, but in another embodiment,

FIG. 6 shows a view, as in FIG. 4, but in a further embodiment,

FIG. 7 shows a view in the circumferential direction of a blade in the region of the shroud,

FIG. 8 shows a view, as in FIG. 2, but in another embodiment,

FIG. 9 shows a sectional view of the blade from FIG. 8 in the region of the shroud according to the sectional lines IX in FIG. 8,

FIG. 10 shows a greatly simplified basic cross section through a turbo machine in the region of a blade row,

FIG. 11 shows a view in the radial direction in the region of a blade according to an arrow XI in FIG. 10,

FIG. 12 shows a longitudinal section through the blade in the region of a shroud ring according to the sectional lines XIV in FIG. 11,

FIG. 13 shows an axial view of the blade in the region of the shroud ring according to an arrow XIII in FIG. 11, and

FIG. 14 shows a view in the circumferential direction of the blade in the region of the shroud ring according to an arrow XIV in FIGS. 10, 11 and 13.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

According to FIG. 1, a turbo machine 1 is equipped with a rotor 2 and with a stator 3. The rotor 2 is mounted rotatably in the stator 3 in the usual way. The turbo machine 1 may basically be a compressor or a turbine. Where a turbine is concerned, it may be a steam turbine or a gas turbine. The turbo machine 1 may be stationary and serve, for example, for driving a generator in a power plant. The turbo machine 1 may likewise be a drive assembly in a vehicle, in particular in an aircraft. However, an implementation of the invention in a configuration of the turbo machine 1 as a stationary gas turbine is preferred.

The rotor 2 has, according to FIG. 1, at least one moving blade row 4 which include a plurality of moving blades 5. The cross section according to FIG. 1 lies in the region of such a moving blade row 4, although only a single moving blade 5 is illustrated for the sake of clarity.

Moreover, the turbo machine 1 is equipped at least with a shroud 8. This shroud 8 is in this case assigned to the moving blade row 4, specifically for all the moving blades 5 of the moving blade row 4. In the embodiment shown in FIG. 1, the shroud 8 is assigned to the moving blade row 4 and is consequently arranged at the outer ends, remote from the rotor 2, of the moving blades 5.

According to principles of the present invention, this shroud 8 is formed either by a shroud ring 32 or by a plurality of shroud segments 33 or by a plurality of shroud plates 34. In this case, the shroud ring 32 is assigned jointly to all the moving blades 5 of the moving blade row 4. In contrast to this, the respective shroud segment 33 is assigned simultaneously to a plurality of adjacent moving blades 5 of the moving blade row 4, while the respective shroud plate 34 is assigned in each case to a single moving blade 5 of the moving blade row 4. The shroud ring 32, the shroud segments 33, and the shroud plates 34 have in common the fact that they in each case form components which are separate with respect to the moving blades 5 and which are fastened to the moving blades 5 in a suitable way. FIG. 1 in each case indicates only a single shroud segment 33; likewise, only a single shroud plate 34 is also indicated by way of example. Although the following description refers explicitly only to the shroud ring 32, it nevertheless implicitly also applies correspondingly to the embodiments with shroud segments 33 or to the embodiments with shroud plates 34.

The shroud ring 32 is preferably produced from one piece, for example by casting or forging. An embodiment is likewise possible in which the shroud ring 32 is assembled from a plurality of portions, in particular from a plurality of ring segments. The shroud ring 32 extends, closed, that is to say without interruption, in the circumferential direction indicated by an arrow 9. The shroud ring 32 is configured to be self-supporting at least insofar as it can be handled as a whole, thus simplifying its mounting and demounting. Furthermore, it can at least partially absorb and discharge in the circumferential direction the high centrifugal forces arising during operation, thus reducing the load on the moving blades 5 connected to it. The shroud ring 33 forms a separate component which is produced independently of the moving blades 5 and, for mounting, is built onto the moving blades 5. For this purpose, the shroud ring 32 and the moving blades 5 are fastened to one another by anchorings 10. The shroud segments 33 used, if appropriate, for forming the shroud 8 are also fastened to at least one of the assigned moving blades 5, preferably to all the assigned moving blades 5, by anchorings 10 of this type. Correspondingly, in the event that the shroud 8 is formed from the shroud plates 34, the individual shroud plates 34 are in each case fastened to the in each case assigned moving blade 5 by anchorings 10 of this type. These anchorings 10 are in this case configured such that they act at least in the radial direction, that is to say can transmit tensile forces between the shroud ring 32 and the moving blades 5 in the radial direction. Moreover, the anchorings 10 are configured such that they are non-destructively releasable. In other words, the mounted shroud ring 32 can be demounted, without the shroud ring 32 being destroyed and without the moving blades 5 being destroyed. This is a critical cost benefit for the later mounting of a repaired or of a new shroud ring 32.

The anchorings 10 can also be configured such that the shroud ring 32, in the mounted state, is fixed with respect to the moving blades 5 in the circumferential direction 9 and/or in the axial direction, that is to say parallel to the axis of rotation 11 of the rotor. A defined fixing of the shroud ring 32 in position in relation to the associated moving blades 5 is thereby achieved. Preferred embodiments for implementing the anchoring 10 are explained in more detail below.

Preferably, the shroud ring 32 is fastened to all the moving blades 5 of the associated moving blade row 4 in each case by at least one such anchoring 10. It is likewise basically possible that the shroud ring 32 is fastened to only some moving blades 5, preferably arranged so as to be symmetrically distributed circumferentially, in each case by at least one such anchoring 10. The anchorings 10 are in each case arranged radially between the shroud ring 32 and the respective moving blade 5.

Basically, an anchoring 10 of this type may be configured in any desired way, for example as a screw, as long as it is suitable for the transmission of tensile force. A preferred configuration of the anchoring 10 is explained in more detail below.

According to FIGS. 2 to 6, each anchoring 10 is equipped with at least one anchor receptacle 12 and 13 and also with at least one anchor 14 and 15 complementary to the respective anchor receptacle 12, 13. FIGS. 2 to 4, 6, 8, and 9 in this case show an anchor receptacle 12 located on the shroud side, that is to say formed in the shroud ring 32, while FIGS. 5 and 6 show an anchor receptacle 13 located on the blade side, that is to say formed in the respective moving blade 5. The anchor cooperating with the shroud-side anchor receptacle 12 is designated by 14, while the anchor cooperating with the moving blade-side receptacle 13 is designated by 15. In the shroud-side anchor receptacle 12, the associated reception profile 16 is open toward the associated moving blade 5. In contrast to this, in the blade-side anchor receptacle 13, the reception profile 16 is open toward the shroud ring 32. The anchor receptacles 12, 13 and their longitudinal directions extend rectilinearly by way of example; embodiments with curved longitudinal directions are likewise possible. Where straight longitudinal directions are concerned, longitudinal edges of the anchor receptacles 12, 13 may run parallel to one another. The longitudinal edges may likewise be leaned or inclined with respect to one another, as a result of which the anchor receptacles 12, 13 taper conically in the mounted direction. Where curved longitudinal directions are concerned, the longitudinal edges may extend along concentric circle arcs. It is likewise possible to have longitudinal edge profiles along circle arcs with offset circle centers in which a conical narrowing in the mounting direction is obtained again for the anchor receptacles 12, 13.

The anchor receptacles 12, 13 are characterized by a reception profile 16 which is constant or conical in its longitudinal direction. This reception profile 16 has at least one undercut 17 accessible radially to engagement. In the exemplary embodiments shown, the reception profile 16 is a T-profile. Other suitable contours, for example a dovetail profile, may likewise serve as reception profiles 16.

The respective anchor 14, 15 has on its outside an anchor profile 18 which is shaped complementarily to the respective reception profile 16. In the present example, therefore, the anchor profiles 18 are fitting T-profiles. In the mounted state, the respective anchor 14, 15 is inserted into the associated anchor receptacle 12, 13, specifically such that its anchor profile 18 effects engagement with the at least one undercut 17 of the reception profile 16. Thus, a form fit active in the radial direction, which is suitable for the transmission of very high forces, is implemented between the shroud ring 32 and the respective moving blade 5.

In the embodiments shown in FIG. 2 to 4 and 8, 9, the anchor 14 is configured as an integral part of the respective moving blade 5. This anchor 14 therefore projects in the radial direction from the blade head, not designated in any more detail, of the respective moving blade 5. In contrast to this, FIG. 5 shows an alternative embodiment, in which the anchor 15 forms an integral part of the shroud ring 32 and consequently projects radially from the latter on a side facing the moving blade 5.

FIG. 6 shows another advantageous embodiment, in which the anchoring 10 has an additional component, to be precise an anchor body 31, which constitutes a separate component with respect to the shroud ring 32 and to the respective moving blade 5. This anchor body 31 is provided with two anchors 14, 15 or is configured such that it has the two anchors 14, 15. Correspondingly, in this embodiment, the anchoring 10 includes both the shroud-side anchor receptacle 12 and the blade-side anchor receptacle 13. The two anchor receptacles 12, 13 are in this case arranged such that they lie radially opposite one another and, in particular, are radially in alignment with one another. Preferably, the two anchor receptacles 12, 13 are designed and arranged congruently to one another. The anchor body 31, here, possesses a double-T-profile or an H-profile. In the mounted state, then, the anchor body 31 is in engagement via its two anchors 14, 15 with both anchor receptacles 12, 13. This embodiment may be advantageous in terms of mounting and demounting, since, for example, it makes it easier to position the shroud ring 32 on the moving blades 5.

In the embodiments of FIG. 2 to 6, the respective anchor receptacle 12, 13 is in each case arranged such that its longitudinal direction extends axially, that is to say parallel to the axis of rotation 11. With such an orientation of the anchor receptacles 12, 13, the anchoring 10 possesses a relatively small length in the longitudinal direction of the anchor receptacle 12, 13. In the case of the axial orientation of the anchor receptacle 12, 13, the anchoring 10 can additionally transmit circumferential forces between the shroud ring 32 and the respective moving blades 5. The mounting of the shroud ring 32 on the moving blades 5 in this case takes place by the respective anchor 14, 15 being introduced into the associated anchor receptacle 12, 13 in its longitudinal direction. The longitudinal direction of the anchor receptacle 12, 13 therefore corresponds to the mounting direction of the anchoring 10. For mounting the anchoring 10, therefore, the reception profile 17 is open at least on one side in the longitudinal direction of the associated anchor receptacle 12, 13.

In the embodiment shown in FIGS. 8 and 9, the anchoring 10 is configured such that the anchor receptacle 12 has an inclination with respect to the axial direction, represented by an arrow 19. Correspondingly, the longitudinal direction of the anchor receptacle 12 extends at an inclination with respect to the axial direction 19. An angle of inclination is in this case designated by 20. Owing to the inclined orientation of the anchor receptacle 12, the anchoring 10 can additionally also transmit axial forces between the shroud ring 32 and the respective moving blade 5.

For the transmission of axial forces, the anchor receptacles 12, 13 may be configured conically in the mounting direction. Additionally or alternatively, the anchor receptacle 12 may be provided, according to FIG. 3, with an axial stop 21 which limits the longitudinal adjustability of the anchor 14 in the anchor receptacle 12. In this embodiment, therefore, the reception profile 17 of the anchor receptacle 12 is closed on one side, for example on the inflow side, in the longitudinal direction of the anchor receptacle 12. Basically, the reception profile 17 of the respective anchor receptacle 12, 13 may be open on both sides in the longitudinal direction of the anchor receptacle 12, 13.

FIG. 8 shows a special embodiment in which the longitudinal direction of the anchor receptacle 12 is inclined, for example, in the same way as the blade profile 22. The angle of inclination 20 in this case lies, for example, in the region of a pitch angle, not designated in any more detail, of the blade profile 22, which is spanned between the inflow direction indicated by an arrow 23 and a longitudinal direction, running through an inflow edge 24 and an outflow edge 25, of the blade profile 22. In this embodiment, a particularly large length, which may be advantageous for mounting, is obtained for the anchoring 10 in its mounting direction, that is to say parallel to the longitudinal direction of the anchor receptacle 12. At the same time, the anchoring 10 can thereby be integrated largely into the outer contour of the respective moving blade 5. Its blade head therefore has to be enlarged only comparatively insignificantly by a thickened cross section. The region with a thickened cross section is indicated in FIG. 3 by a curly bracket and is designated by 26. The anchoring 10 therefore has a comparatively slender build.

The relatively large length of the anchoring 10 in the longitudinal direction of the blade profile 22 according to the embodiment shown in FIG. 8, like the relatively large width of the anchoring 10 parallel to the longitudinal direction of the blade profile 22 according to the other embodiments, has the effect, in the case of a distortion of the respective moving blade 5 when the turbo machine is in operation, of a tilting of the anchor 14, 15 in the respective anchor receptacle 12, 13. This tilting leads, in turn, to a nonpositive connection which reinforces the holding force between the shroud ring 32 and the respective moving blade 5.

In an advantageous development, there may be provision for securing the respective anchor 14, 15 in the associated anchor receptacle 12, 13 by a shrink fit, thus leading to a prestressed, nonpositive coupling between the shroud ring 32 and the respective moving blade 5.

The respective anchoring 10 may be configured, by an appropriate coordination of the anchor receptacle 12, 13 and of the anchor 14, 15, as a sliding fit which makes mounting easier parallel to the longitudinal direction of the anchor receptacle 12, 13. In this case, it may be expedient to equip the respective anchoring 10 with a securing device 35. This securing device 35 is in this case configured such that, in the mounted state of the shroud ring 32, it fixes the relative position between the anchor receptacle 12, 13 and anchor 14, 15 within the respective anchoring 10. For example, the securing device 35 may be formed by a pin-shaped securing element 36 which extends transversely with respect to the longitudinal direction of the anchor receptacle 12, 13, preferably radially. In the embodiments of FIGS. 4 and 5, this securing element 36 penetrates with a positive fit in each case, on the one hand, into a first orifice, not designated in any more detail and formed in the shroud ring 32, and, on the other hand, at the same time into a second orifice, not designated in any more detail and formed in the respective moving blade 5. In the embodiment according to FIG. 6, the securing element 32 additionally penetrates through the anchor member 31 in a through orifice formed in the latter and not designated in any more detail.

As may be gathered from FIGS. 4 to 6, in special embodiments the shroud ring 32 may contain cooling duct structures 27 which are indicated here merely diagrammatically by broken lines. These cooling duct structures 27 serve for cooling the shroud ring 32 and may, for example, form a coolant path remaining inside the shroud ring 32 and/or have outlet orifices 28 which end on the surface of the shroud ring 32 and through which coolant can emerge also in order to form a cooling film on the surface of the shroud ring 32. In the mounted state, the cooling duct structures 27 of the shroud ring 32 communicate with cooling duct structures 29 which are formed inside the respective moving blade 5. Thus, the cooling duct structures 27 of the shroud ring 32 are supplied with coolant via the cooling duct structures 29 of the respective moving blade 5. In this case, the separate type of construction of the shroud ring 32 independent of the moving blades 5 is beneficial to the formation of complex cooling duct structures 27 in the shroud ring 32, since these can be produced in the shroud ring 32 before mounting on the moving blades 5.

In this case, it is clear that suitable sealing devices, not illustrated here, may be provided in the contact region between the shroud ring 32 and the respective moving blades 5, in order to connect the shroud-side cooling duct structures 27 to the blade-side cooling duct structures 29 so as to be outwardly, fluidly sealed off.

According to FIG. 7, in an exemplary development, the shroud ring 32 may be equipped with a sealing structure 30. This is, in this case, arranged on a side of the shroud ring 32 which faces away from the moving blades 5. The sealing structure 30 is likewise indicated here merely by a broken line and has, for example, the form of a radially projecting peripheral web closed in the circumferential direction 9, what is known as a fin. The sealing structure 30 then cooperates with a radially adjacent wall either of the rotor 2 or of the stator 3 in order to form an axial seal of the respective moving blade row 4. For example, the web indicated in FIG. 7 penetrates into a corresponding annular groove in order thereby to generate the action of a labyrinth seal. There are many models in the prior art for the configuration of sealing structures 30 of this type, and therefore they do not have to be dealt with in any more detail here. Other sealing structures 30 are, for example, a brushing structure which cooperates with a brushable counterstructure, one of these structures forming the sealing structure 30 of the shroud ring 32, while the other structure is then formed on the rotor 2 or on the stator 3.

According to FIGS. 10 to 14, a possible embodiment of the shroud 8 as a shroud ring 108 is described.

According to FIG. 10, a turbo machine 101 is equipped with a rotor 102 and with a stator 103. The rotor 102 is mounted rotatably in the stator 103 in the usual way. The turbo machine 101 may basically be a compressor or a turbine. The turbo machine 101 may be stationary and, for example, serve for driving a generator in a power plant. The turbo machine 101 may likewise basically be a drive assembly in a vehicle, in particular in an aircraft. However, it is preferred to implement the invention in a configuration of the turbo machine 101 as a stationary gas turbine.

According to FIG. 10, the rotor 102 has at least one moving blade row 104 which includes a plurality of moving blades 105. The cross section according to FIG. 10 lies in the region of such a moving blade row 104, although only a single moving blade 105 is illustrated for the sake of clarity.

According to principles of the invention, then, the turbo machine 101 may be equipped at least with a shroud ring 108. This shroud ring 108 is in this case assigned to one of the moving blades row 104, specifically jointly for all the moving blades 105 of the respective moving blade row 104. In the embodiment shown in FIG. 10, the shroud ring 108 is assigned to the moving blade row 104 and is therefore arranged at the outer ends, remote from the rotor 102, of the moving blades 105.

The shroud ring 108 is in this case preferably produced from one piece, for example by casting or forging. An embodiment is likewise possible in which the shroud ring 108 is assembled from a plurality of portions, in particular from a plurality of ring segments.

The shroud ring 108 is a separately produced component with respect to the moving blades 105. As a result, an optimization of the shroud ring 108 in terms of strength, by an appropriate choice of material and in terms of aerodynamics by means of appropriate shaping, can be implemented.

The shroud ring 108 extends, closed, that is to say without interruption, in the circumferential direction indicated by an arrow 109. The shroud ring 108 has a self-supporting configuration, with the result that it can absorb in it the forces arising during operation. This property is of enhanced interest particularly in the variant according to FIG. 10, since high centrifugal forces arise there during operation as a result of the rotation of the rotor 102. Furthermore, the shroud ring 108 forms a separate component which is produced independently of the moving blades 105 and, for mounting, is built onto the moving blades 105. For this purpose, the shroud ring 108 and the moving blades 105 are coupled to one another in the coupling regions 1010.

These coupling regions 1010 may in this case be configured such that, in the mounted state, the shroud ring 108 is radially free with respect to the moving blades 105. Thus, in the embodiment according to FIG. 10, the shroud ring 108 can increase its diameter due to the active centrifugal forces and because of thermal expansion, without tensile forces thereby being introduced into the moving blades 105. Furthermore, the coupling regions 1010 may also be configured such that, in the built-on state, the shroud ring 108 is fixed with respect to the moving blades 105 in the axial direction, that is to say parallel to the axis of rotation 1011 of the rotor 102, and, additionally or alternatively, in the circumferential direction 109. A defined fixing in position of the shroud ring 108 in relation to the associated moving blades 105 is thereby achieved. A preferred embodiment for implementing the radial freedom and the axial and tangential securing of the shroud ring 108 in relation to the moving blades 105 is explained in more detail below with reference to FIGS. 11 and 12.

According to FIGS. 11 and 12, the shroud ring 108 may be secured with the aid of a securing device 1012 to at least one of the moving blades 105 assigned to the shroud ring. Basically, the shroud ring 108 can be attached to each moving blade 105 by at least one such securing device 1012. FIGS. 11 and 12 in this case illustrate two different variants of the securing device 1012 and 1012′ which can be implemented cumulatively or alternatively. The respective securing device 1012, 1012′ is characterized in that it secures the shroud ring 108 to the respective moving blade 105 in the axial direction and/or in the circumferential direction 109 against relative adjustments, that is to say implements the abovementioned fixing. The respective securing device 1012, 1012′ is in this case formed radially between the shroud ring 108 and the respective moving blade 105.

For this purpose, in the preferred embodiment shown here, the securing device 1012, 1012′ is equipped with at least one securing member 1013 or 1013′. The securing member 1013, 1013′ is arranged radially movably on the respective moving blade 105. For this purpose, for example, it is mounted adjustably, guided in the radial direction, in a correspondingly shaped guide orifice 1014 or 1014′.

The two securing devices 1012, 1012′, which are reproduced here by way of example, differ from one another, for example, in the form of their securing members 1013, 1013′. Whereas one securing member 1013 is configured as a cylindrical bolt, the other securing member 1013′ is in the form of a rectilinear web which extends between an inflow edge, not designated in any more detail, of the blade profile and an outflow edge, not designated in any more detail, of the blade profile.

The respective securing device 1012, 1012′ includes, for each securing member 1013, 1013′, an associated securing orifice 1015 or 1015′ which is formed on the shroud ring 108 and is arranged in alignment with the guide orifice 1014, 1014′. The respective securing orifice 1015, 1015′ is in this case coordinated with the associated securing member 1013, 1013′ such that the securing member 1013, 1013′ can penetrate in the radial direction into the associated securing orifice 1015, 1015′. As soon as the securing member 1013, 1013′ projects so far out of its guide orifice 1014, 1014′ that it projects into the securing orifice 1015, 1015′, the desired fixing or securing in the axial direction and in the circumferential direction is obtained. Both the guide orifices 1014, 1014′ and the securing orifices 1015, 1015′ are shaped complementarily to the respective securing member 1013, 1013′.

Since the respective securing member 1013, 1013′ is mounted radially movably both in the associated guide orifice 1014, 1014′ and in the associated securing orifice 1015, 1015′, the radial degree of freedom for the shroud ring 108 in relation to the moving blade 105 is thereby ensured at the same time.

In the case of the shroud ring 108 assigned to the moving blade row 104, the penetration of the securing member 1013, 1013′ into the securing orifice 1015, 1015′ takes place, when the turbo machine 101 is in operation, as a result of the prevailing centrifugal forces, since these drive the securing member 1013, 1013′ radially outward, that is to say into the respective securing orifice 1015, 1015′. The dimensioning of the respective securing orifice 1015, 1015′ is in this case expediently selected such that, when a radial stop, not designated in any more detail, is reached, the securing member 1013, 1013′ is still arranged partially in the guide orifice 1014, 1014′.

So that the desired securing action or fixing action can likewise be ensured when the turbo machine 101 is at a standstill, the securing member 1013, 1013′ may be prestressed radially in the direction of the securing orifice 1015, 1015′ with the aid of a securing spring 1016 or 1016′. Moreover, during the mounting of the shroud ring 108, the radially prestressed securing member 1013, 1013′ ensures an audible latching when the predetermined relative position between the shroud ring 108 and the associated moving blade 105 is reached.

To accommodate the respective securing device 1012, 1012′, the associated moving blade 105 may be thickened in the region of its blade head transversely to its blade profile. This thickened head zone is identified in FIG. 12 by a curly bracket and is designated by 1017.

According to a preferred embodiment, the mounting of the shroud ring 108 expediently takes place such that the shroud ring 108, once mounted, can, if required, be removed from the moving blades 105 again non-destructively. This non-destructive release from the moving blades 105 can be implemented particularly simply in the embodiment shown here, which works to secure or to fix by the securing device 1012, 1012′. For example, the shroud ring 108 contains for each securing member 1013, 1013′ at least one unlocking orifice 1018 or 1018′. This unlocking orifice 1018, 1018′ is in this case positioned such that the respective securing member 1013, 1013′ can be driven through it out of the securing orifice 1015, 1015′, using a suitable tool capable of being introduced into the unlocking orifice 1018, 1018′. The respective securing member 1013, 1013′ can thus be adjusted in the guide orifice 1014, 1014′, counter to the securing spring 1016, 1016′, until the shroud ring 108 is freed from the respective moving blade 105.

According to FIG. 13, in a special embodiment, the shroud ring 108 may contain cooling duct structures 1019 which are indicated here merely diagrammatically by broken lines. These cooling duct structures 1019 serve for cooling the shroud ring 108 and, for example, may form a coolant path remaining inside the shroud ring 108 and/or may include outlet orifices 1020 which end on the surface of the shroud ring 108 and through which coolant can emerge also in order to form a cooling film on the surface of the shroud ring 108. In the mounted state, the cooling duct structures 1019 of the shroud ring 108 communicate with cooling duct structures 1021 which are formed inside the respective moving blade 105. Thus, the cooling duct structure 1019 of the shroud ring 108 is supplied with coolant via the cooling duct structures 1021 of the respective moving blade 105. In this case, the separate type of construction of the shroud ring 108 independent of the moving blades 105 is beneficial to the formation of complex cooling duct structures 1019 in the shroud ring 108, since these can be produced in the shroud ring 108 before mounting on the moving blades 105. It is clear that suitable sealing devices may be provided for the fluidic coupling of the shroud-side cooling duct structures 1019 to the blade-side cooling duct structures 1021.

According to FIG. 14, in a development of the invention, the shroud ring 108 may be equipped with a sealing structure 1022. This is in this case arranged on a side of the shroud ring 108 which faces away from the moving blades 105. The sealing structure 1022 is likewise indicated here merely by a broken line and, for example, has the form of a radially projecting peripheral web closed in the circumferential direction, what is known as the fin. The sealing structure 1022 then cooperates with a radially adjacent wall either of the rotor 102 or of the stator 103 in order to form an axial seal of the respective moving blade row 104. For example, the web indicated in FIG. 14 penetrates into a corresponding annular groove in order thereby to generate the action of a labyrinth seal. There are many models in the prior art for the configuration of sealing structures 1022 of this type, and therefore they do not have to be dealt with in any more detail here. Other sealing structures 1022 are, for example, a brushing structure which cooperates with a brushable structure, one of these structures forming the sealing structure 1022 of the shroud ring 108, while the other structure is then formed on the rotor 102 or on the stator 103.

LIST OF REFERENCE SYMBOLS

-   -   1 Turbo machine     -   2 Rotor     -   3 Stator     -   4 Moving blade row     -   5 Moving blade     -   6 Guide vane row     -   7 Guide vane     -   8 Shroud     -   9 Circumferential direction     -   10 Anchoring     -   11 Axis of rotation     -   12 Anchor receptacle     -   13 Anchor receptacle     -   14 Anchor     -   15 Anchor     -   16 Reception contour     -   17 Undercut     -   18 Anchor contour     -   19 Axial direction     -   20 Angle of inclination     -   21 Stop     -   22 Blade profile     -   23 Inflow direction     -   24 Inflow edge     -   25 Outflow edge     -   26 Thickened region of 5, 7     -   27 Cooling duct structure     -   28 Outlet orifice     -   29 Cooling duct structure     -   30 Sealing structure     -   31 Anchor body     -   32 Shroud ring     -   33 Shroud segment     -   34 Shroud plate     -   35 Securing device     -   36 Securing element     -   101 Turbo machine     -   102 Rotor     -   103 Stator     -   104 Moving blade row     -   105 Moving blade     -   106 Guide vane row     -   107 Guide vane     -   108 Shroud ring     -   109 Circumferential direction     -   1010 Coupling region     -   1011 Axis of rotation     -   1012, 1012′ Securing device     -   1013, 1013′ Securing member     -   1014, 1014′ Guide orifice     -   1015, 1015′ Securing orifice     -   1016, 1016′ Securing spring     -   1017 Thickened region of 105, 107     -   1018, 1018′ Unlocking orifice     -   1019 Cooling duct structure in 108     -   1020 Coolant outlet orifice     -   1021 Cooling duct structure in 105, 107     -   1022 Sealing structure

While the invention has been described in detail with reference to exemplary embodiments thereof, it will be apparent to one skilled in the art that various changes can be made, and equivalents employed, without departing from the scope of the invention. The foregoing description of the preferred embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto, and their equivalents. The entirety of each of the aforementioned documents is incorporated by reference herein. 

1. A turbo machine comprising: a rotor having at least one moving blade row with a plurality of moving blades; a stator having at least one guide vane row with a plurality of guide vanes; a shroud assigned to all the moving blade tips of at least one moving blade row; wherein the shroud is configured and arranged to be self-supporting so that it can at least partially absorb the centrifugal forces arising during operation of the turbo machine and discharge them in the circumferential direction; wherein the shroud comprises a shroud ring assigned jointly to all the moving blades of said at least one moving blade row and is circumferentially closed; and wherein the shroud ring is fastened to at least a plurality of the moving blades of said at least one moving blade row each via at least one, at least radially active, non-destructively releasable, anchoring.
 2. The turbo machine as claimed in claim 1, wherein: the at least one anchoring has at least one shroud-side anchor receptacle formed in the shroud ring and which is open toward the respective moving blade and has a reception profile, constant in the longitudinal direction of said anchor receptacle, with at least one undercut accessible radially; and the at least one anchoring has at least one anchor with an anchor profile configured complementarily to the reception profile, which at least one anchor is positioned in the anchor receptacle and is in engagement via its anchor profile with the at least one undercut.
 3. The turbo machine as claimed in claim 1, wherein: the at least one anchoring has at least one blade-side anchor receptacle formed in the respective moving blade and which is open toward the shroud and has a reception profile, constant or conical in the longitudinal direction of said anchor receptacle, with at least one undercut accessible radially; and the at least one anchoring has at least one anchor with an anchor profile configured complementarily to the reception profile, which at least one anchor is positioned in the anchor receptacle and is in engagement via its anchor profile with the at least one undercut.
 4. The turbo machine as claimed in claim 2, wherein: the at least one anchor cooperating with the shroud-side anchor receptacle is an integral part of the respective moving blade and projects radially from its moving blade head; or the at least one anchor cooperating with the blade-side anchor receptacle is an integral part of the shroud ring and projects radially from the shroud ring; or both.
 5. The turbo machine as claimed in claim 3, wherein: the at least one anchoring has both at least one shroud-side anchor receptacle and at least one blade-side anchor receptacle arranged radially opposite one another; and the at least one anchoring has at least one anchor body which is a separate component from the shroud ring and from the moving blades, the at least one anchor body including the at least one anchor cooperating with the shroud-side anchor receptacle and the at least one anchor cooperating with the blade-side anchor receptacle.
 6. The turbo machine as claimed in claim 2, wherein: the at least one anchor receptacle is arranged such that its longitudinal direction extends axially; or the at least one anchor receptacle is arranged such that its longitudinal direction extends at an inclination with respect to the axial direction; or the at least one anchor receptacle is arranged such that its longitudinal direction extends essentially parallel to the longitudinal direction of the moving blade profile.
 7. The turbo machine as claimed in claim 2, wherein: the reception profile of the at least one anchor receptacle is closed on one side in its longitudinal direction, or is open only on the outflow side, or both; or the at least one anchoring comprises a securing device configured and arranged to fix the relative position between the at least one anchor receptacle and the at least one anchor; or both.
 8. The turbo machine as claimed in claim 1, wherein: the shroud ring contains cooling duct structures configured and arranged to cool the shroud ring when the turbo machine is in operation; the moving blades comprise cooling duct structures configured and arranged to cool the moving blades when the turbo machine is in operation; and the shroud ring cooling duct structures are in fluid communication with the moving blade cooling duct structures.
 9. The turbo machine as claimed in claim 1, wherein the shroud ring comprises, on a side facing away from the moving blades, a sealing structure configured and arranged to axially seal the gap between the shroud ot the at least one moving blade row) and the stator when the turbo machine is in operation.
 10. A shroud to be mounted on moving blades of a moving blade row of a turbo machine, the turbo machine being equipped with at least one moving blade row having a plurality of moving blades and with at least one guide vane row having a plurality of guide vanes, the shroud comprising: a shroud ring assigned jointly to all the moving blades of the moving blade row and circumferentially closed, the shroud ring being configured and arranged to be fastened to at least a plurality of the moving blades of the moving blade row each via at least one at least radially active, non-destructively releasable, anchoring.
 11. The turbo machine as claimed in claim 3, wherein: the at least one anchor receptacle is arranged such that its longitudinal direction extends axially; or the at least one anchor receptacle is arranged such that its longitudinal direction extends at an inclination with respect to the axial direction; or the at least one anchor receptacle is arranged such that its longitudinal direction extends essentially parallel to the longitudinal direction of the moving blade profile.
 12. The turbo machine as claimed in claim 3, wherein: the reception profile of the at least one anchor receptacle is closed on one side in its longitudinal direction, is open only on the outflow side, or both; or the at least one anchoring comprises a securing device configured and arranged to fix the relative position between the at least one anchor receptacle and the at least one anchor; or both. 